Michael A. Reveley

The Genetic Basis of Cerebral Ventricular Volume

Cerebral ventricular volume, assessed by computed tomography, is a genetically determined trait. In a series of 18 monozygotic and 18 dizygotic twins, heritability values ranged from 82% to 85% depending on the method of calculation.

Aqueduct stenosis and schizophrenia

Three patients with hydrocephalus and aqueduct stenosis are described, who also have schizophrenia defined according to strict diagnostic criteria. There are no previous reports of such an association.

Increased platelet monoamine oxidase activity in affective disorders.

Platelet monoamine oxidase activity was determined in 52 unipolar depressive patients, 26 patients with bipolar affective disorder and 48 controls using phenylethylamine as substrate. Unipolar depressive patients of either sex and bipolar depressive women showed significantly higher platelet MAO activity than controls. Women had higher activity than men. Neither age nor serum lithium level correlated with enzyme activity and there was no significant change in activity after the institution of lithium treatment.

Decreased urinary output of conjugated tyramine is associated with lifetime vulnerability to depressive illness

In a group of normal pregnant women whose psychiatric histories were unknown, those with the lowest output of urinary tyramine (free plus conjugated) after an oral tyramine load had a significantly higher lifetime incidence of depressive illness compared with those with the highest output. as none of the women were suffering from depression at the time of tyramine loading, it seems likely that this decreased excretion of tyramine is associated in some way with vulnerability to depressive illness, whether puerperal or nonpuerperal.

A genetic study of platelet phenolsulphotransferase activity in normal and schizophrenic twins

In a series of 19 identical and 16 fraternal twin pairs, the activities of the two forms of the enzyme, phenolsulphotransferase, denominated M and P, were investigated in blood platelets. Both were shown to be under a high degree of genetic control. No differences were found between 11 schizophrenic patients from discordant twin pairs, compared with their well cotwins and 12 male and female volunteer twin pairs, for either form of the enzyme.

Urinary MAO inhibitor in psychiatric illness

Normal human urine contains an endogenous monoamine oxidase inhibitor. We have now investigated its activity in urine samples from psychiatric patients in various diagnostic categories. Significantly higher values were observed in alcoholics recently withdrawn from ethanol, compared with controls. Inhibitory activity was not specifically related to primary affective disorders. Inhibitor output may be positively related to certain symptom clusters rather than to disease entities (i.e. alcohol withdrawal, agitation, and hyperkinesis). Significantly lower inhibitor output was also found in a small group of patients with chronic schizophrenia.

The relationship of twinning to the familial-sporadic distinction in schizophrenia

Cerebral ventricular enlargement in schizophrenia may occur more often in the absence of a family history of the disorder, suggesting that it is related to some non-genetic component of aetiology. This paper shows the finding to be much more apparent in a group of twins than in a similar group of singletons. Previous studies have shown twins in general to have larger cerebral ventricles than non-twins; we suggest that it is the greater susceptibility of twins to obstetric complications that is responsible for both the larger cerebral ventricles found in normal twins, and the very marked increase in ventricular size found in family history negative schizophrenic twins. We go on to consider evidence relating to a possible increased susceptibility of twins to develop schizophrenia.

Dopamine Metabolism in Human Brain

The vast literature on dopamine which now exists attests to the pre-eminence it has achieved among the monoamines, since its first recognition as a neurotransmitter in the late 1950’s (Carlsson, 1959). Much of our latter-day interest has been sustained by the finding that L-dopa administration to parkinsonian patients, resulting in dopamine generation in the central nervous system, gives rise to substantial therapeutic benefit (Cotzias et al., 1967). More recently, attention has focussed on the possible role of the amine in schizophrenia (Randrup and Munkvad, 1968). Despite this preoccupation with dopamine, certain metabolic pathways connected with its generation or disposition have still been underinvestigated, particularly in man. This paper sets out to provide a brief evaluation of the importance of four of these pathways in the human brain, L-aromatic amino acid decarboxylase, L-dopa transaminase, monoamine oxidase and phenolsulphotransferase.